Modern transportation and numerous stationary industrial engines require oil to function. The oil plays a vital role in lubricating surfaces, carrying away harmful particulate, and cooling the engine. Particulates carried in the oil are removed by cycling the oil through a filter. The typical oil filter for this purpose comprises a substantial metal base, of steel or the like, a lighter weight canister, and the filter element per se, usually a mass of fibrous material enclosed by the canister and arranged to trap particulates in the oil and separate them. The metal base is perforated to provide for oil passage into the canister. Periodic replacement of the oil is essential to engine life. At such replacement the filter is usually replaced as well. This process generates tens of millions of used filters annually. Disposal of these filters is an environmental problem. First, their oil content must be well drained. Then the oil impregnated filter element must be captured for environmentally safe disposal, and the metal components, the canister and base, directed to appropriate recyclers of these types of metal.
The problem with recovery and recycle as just outlined is that as a practical matter the gathering and processing of millions of units requires an enormous amount of labor as the units are difficult to handle, hard to disassemble, and so numerous as to overwhelm ordinary scrap recyclers.